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Mechanism, kinetics, and pathways of self-sensitized sunlight photodegradation of phenylarsonic compounds
- Source :
- Water Research. 96:136-147
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- Being highly water-soluble, phenylarsonic feed additives discharged in animal wastes can easily accumulate in surface water bodies. The photodegradation mechanism, kinetics, and pathways of p-arsanilic acid (p-ASA), 4-hydrophenylarsonic acid (4-HPAA), and phenylarsonic acid (PAA) in water under simulated and natural sunlight irradiation were investigated. The -AsO(OH)2 group was cleaved from the aromatic ring during photodegradation, and p-benzoquinone and p-hydroquinone were formed as the major organic degradation intermediates. Experimental results did not indicate any significant direct photolysis of the phenylarsonic compounds under simulated and natural sunlight irradiation, but consistently showed that they sensitized the formation of singlet oxygen, which was responsible for their photodegradation and oxidation of the As(III) released. A simple (1)O2-based "heterogeneous" model was developed, which could well describe the kinetics of (1)O2 formation and phenylarsonic compound photodegradation under various conditions. Indirect photolysis caused by inorganic ions commonly present in natural waters was negligible, while natural organic matter could significantly inhibit their photodegradation. The half-lives of p-ASA, 4-HPAA, and PAA photodegradation under simulated sunlight irradiation (765 W m(-2), 25 °C) were 11.82 ± 0.19, 20.06 ± 0.10, and 135 ± 6.0 min, respectively, while their degradation rates under natural sunlight in the Pearl River Delta of southern China were 5 times slower due to lower irradiation intensity and water temperatures (19-23 °C).
- Subjects :
- Environmental Engineering
Kinetics
02 engineering and technology
010501 environmental sciences
Inorganic ions
Photochemistry
01 natural sciences
chemistry.chemical_compound
Benzoquinones
Irradiation
Photodegradation
Waste Management and Disposal
0105 earth and related environmental sciences
Water Science and Technology
Civil and Structural Engineering
Photolysis
Singlet oxygen
Ecological Modeling
Photodissociation
Phenylarsonic acid
021001 nanoscience & nanotechnology
Pollution
chemistry
Sunlight
Degradation (geology)
0210 nano-technology
Water Pollutants, Chemical
Subjects
Details
- ISSN :
- 00431354
- Volume :
- 96
- Database :
- OpenAIRE
- Journal :
- Water Research
- Accession number :
- edsair.doi.dedup.....6d56add4d16a0f1b888165a5c2dab2dc